Submission #310794

#	Time	Username	Problem	Language	Result	Execution time	Memory
310794		VROOM_VARUN	Pipes (BOI13_pipes)	C++14	100 / 100	241 ms	25520 KiB

pipes

/*
ID: varunra2
LANG: C++
TASK: pipes
*/

#include <bits/stdc++.h>
using namespace std;

#ifdef DEBUG
#include "lib/debug.h"
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define debug_arr(...) \
  cerr << "[" << #__VA_ARGS__ << "]:", debug_arr(__VA_ARGS__)
#pragma GCC diagnostic ignored "-Wsign-compare"
//#pragma GCC diagnostic ignored "-Wunused-parameter"
//#pragma GCC diagnostic ignored "-Wunused-variable"
#else
#define debug(...) 42
#endif

#define EPS 1e-9
#define IN(A, B, C) assert(B <= A && A <= C)
#define INF (int)1e9
#define MEM(a, b) memset(a, (b), sizeof(a))
#define MOD 1000000007
#define MP make_pair
#define PB push_back
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.end(), cont.begin()
#define x first
#define y second

const double PI = acos(-1.0);
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef map<int, int> MPII;
typedef multiset<int> MSETI;
typedef set<int> SETI;
typedef set<string> SETS;
typedef vector<int> VI;
typedef vector<PII> VII;
typedef vector<VI> VVI;
typedef vector<string> VS;

#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define trav(a, x) for (auto& a : x)
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef vector<int> vi;
#pragma GCC diagnostic ignored "-Wsign-compare"
// util functions

int n, m;
vector<VII> adj;
VI vals;
VI ret;
VI deg;
MPII in;

void init() {
  adj.resize(n);
  vals.resize(n);
  ret.resize(m);
  deg.resize(n);
}

void getDeg() {
  for (int i = 0; i < n; i++) {
    deg[i] = sz(adj[i]);
  }
}

void pr() {
  for (int i = 0; i < m; i++) {
    cout << ret[i] * 2 << '\n';
  }
}

void dfs(int u) {
  // debug(u);
  deg[u] = 0;
  for (auto& x : adj[u]) {
    if (deg[x.x] > 0) {
      vals[x.x] -= vals[u];
      deg[x.x]--;
      ret[x.y] = vals[u];
      vals[u] = 0;
      if (deg[x.x] <= 1) dfs(x.x);
    }
  }
}

void bad() {
  cout << "0\n";
  exit(0);
}

void solvetree() {
  getDeg();
  for (int i = 0; i < n; i++) {
    // debug(deg[i], "here", i);
    if (deg[i] == 1) {
      dfs(i);
    }
  }

  // debug(vals);
  // debug(deg);

  for (int i = 0; i < n; i++) {
    if (vals[i] != 0) {
      bad();
    }
  }

  pr();
}

void dfscyc(int u, VI& cmp) {
  deg[u] = 0;
  cmp.PB(u);
  in[u] = 1;
  for (auto& x : adj[u]) {
    if (deg[x.x] > 0) {
      dfscyc(x.x, cmp);
      break;
    }
  }
}

int get(int u, int v) {
  trav(x, adj[u]) {
    if (x.x == v) return x.y;
  }
  return -INF;
}

void solvecyc() {
  getDeg();
  for (int i = 0; i < n; i++) {
    if (deg[i] == 1) {
      dfs(i);
    }
  }

  VI cmp;

  for (int i = 0; i < n; i++) {
    if (deg[i] > 0) {
      dfscyc(i, cmp);
      break;
    }
  }

  if (sz(cmp) % 2 == 0) bad();

  int sm = 0;

  for (int i = 0; i < sz(cmp); i++) {
    if (i % 2)
      sm -= vals[cmp[i]];
    else
      sm += vals[cmp[i]];
  }

  if (sm % 2) bad();

  sm /= 2;

  ret[get(cmp.back(), cmp[0])] = sm;

  for (int i = 0; i < sz(cmp) - 1; i++) {
    int ind = get(cmp[i], cmp[i + 1]);
    ret[ind] = vals[cmp[i]] - sm;
    sm = ret[ind];
  }

  pr();
}

void solvemultcyc() { bad(); }

int main() {
// #ifndef ONLINE_JUDGE
  // freopen("pipes.in", "r", stdin);
  // freopen("pipes.out", "w", stdout);
// #endif
  cin.sync_with_stdio(0);
  cin.tie(0);

  cin >> n >> m;

  init();

  for (int i = 0; i < n; i++) {
    cin >> vals[i];
    // vals[i] *= -1;
  }

  for (int i = 0; i < m; i++) {
    int u, v;
    cin >> u >> v;
    u--, v--;
    adj[u].PB(MP(v, i));
    adj[v].PB(MP(u, i));
  }

  if (m == n - 1) {
    solvetree();
  } else if (m == n) {
    solvecyc();
  } else {
    solvemultcyc();
  }

  return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 70 / 70